Impact of the metal-to-artery ratio on clinical outcomes in left main and nonleft main bifurcation: insights the RAIN-CARDIOGROUP VII study (veRy thin stents for patients with left mAIn or bifurcatioN in real life)

Introduction The impact on clinical outcomes of the metal coverage on the coronary surface (namely the metal-to-artery ratio) of currently used drug-eluting stents (DESs) has not been defined. Methods All patients with a left main or bifurcation stenosis treated with percutaneous coronary intervention (PCI) using ultrathin stents (struts thinner than 81 mu m) were enrolled with a prospective multicentre fashion. The rate of device-oriented endpoint [DOE, defined as a composite of target lesion revascularization (TLR) and stent thrombosis] was the primary endpoint, while its single components were the secondary ones, evaluated according to the metal-to-artery ratio. Results After 14 +/- 10.4 months 62 (7.5%) of 830 patients undergoing PCI on left main experienced a DOE without differences in the metal-to-artery ratio (14.5 +/- 2.1 vs. 14.4 +/- 1.9,P = 0.51). Fifty out (2.4%) of 2082 patients treated with PCI on a coronary bifurcation other than left main experienced a DOE, with a higher mean metal-to-artery ratio (15.3 +/- 2.1 vs. 14.6 +/- 2,P = 0.01). At multivariate analysis, together with hypertension and diabetes, the metal-to-artery ratio was an independent predictor of DOE (hazard ratio 1.7 : 1.02-1.34,P = 0.02) in nonleft main PCI. When analysed for diameter, we found a significant correlation with DOE when the stent diameter was inferior to 3.0 mm (hazard ratio 1.21: 1.06-1.38,P < 0.01, all 95% confidence interval); this result was mainly consistent for patients treated with provisional stenting. The metal-to-artery ratio does not impact on outcomes in left main PCI, both in the provisional or two-stent technique, and generally when a drug-eluting stent more than 3.5 mm in diameter is implanted. Regarding nonleft main PCI, it is independently related to DOE and TLR, especially for DES with a diameter of 3.25 mm or less. Conclusion The metal-to-artery ratio does not impact on outcomes in left main PCI, both in the provisional or two-stent technique, and generally when a drug-eluting stent more than 3.5 mm in diameter is implanted. Regarding nonleft main PCI, it is independently related to DOE and TLR, especially for DES with a diameter of 3.25 mm or less.